It has been reported by the prior art that the pyridyl cyanoguanidines have anti-tumour activities. For example, U.S. Pat. No. 5,563,160 discloses a series of pyridyl cyanoguanidines which inhibit cancer cells. However, only experimental data of several compounds in the general formula were provided in the patent.
The inventors of the present application conducted a research on pyridyl cyanoguanidines, and found that some pyridyl cyanoguanidines with particular structures had unexpected biological activities. The present application is thereby provided.